Difference between .MPEG and.MPG

[Batman]

I have noticed that files that end in the extension .mpeg have a significantly better resolution than a file of similar size that has the extension .mpg. Why is that so? A 50 mb .mpeg file produces a good quality 22 minute file. a 22 minute file compressed to 50 mb in .mpg extension has awful quality. What is the difference?

[setarip]

Although not "official", the .MPEG is frequently used to denote MPEG2 format as opposed to MPEG1 format. MPEG2 offers a better compression scheme vis-a-vis MPEG1- as one might expect of a successor format.

[Batman]

Thanks There is a striking difference in the compression and quality of the two formats.